The Infernal Tower

The whole repeating mechanism is located in a single, three-tiered tower of 5.15 millimeters height and dubbed the ‘Infernal Tower’ by the watchmakers due to its complex construction.
The different levels are made up of the minute snail, three quarter snails (one for each quarter in an hour), the hour snail and their corresponding cams. By this novel arrangement, the watchmakers for the first time were able to eliminate the need for a so-called ‘surprise piece’ which prevents chiming watches from chiming the last quarter hour in minutes instead of the new hour.